Patterns of individual differences in reduction: Implications for listener-oriented theories

Many listener-oriented theories of phonetic reduction assume that the talker has tacit knowledge of an interlocutor’s mental state, and consequently predict that talkers with poor theory of mind should exhibit inconsistent behavior between semantic contexts. This study examined effects of individual differences in theory of mind skills on extent of phonetic reduction in three acoustic domains (word duration, vowel duration, and vowel dispersion) in contexts of high and low semantic predictability. Overall, a trend was observed whereby participants with stronger theory of mind skills produced less phonetic reduction than participants with poorer theory of mind skills. These results are not consistent with the predictions of listener-oriented theories, or indeed other contemporary theories. We conclude that individual differences ought to be considered in more detail by phonetic theory.